--- np2/bios/bios1b.c	2003/12/28 14:33:34	1.8
+++ np2/bios/bios1b.c	2004/01/13 05:30:58	1.10
@@ -995,6 +995,41 @@ void bios0x1b(void) {
 	BYTE	ret_ah;
 	REG8	flag;
 
+#if 0			// bypass to disk bios
+	REG8	seg;
+	UINT	sp;
+
+	seg = mem[0x004b0 + (CPU_AL >> 4)];
+	if (seg) {
+		TRACEOUT(("call by %.4x:%.4x",
+							i286_memword_read(CPU_SS, CPU_SP+2),
+							i286_memword_read(CPU_SS, CPU_SP)));
+		sp = CPU_SP;
+		i286_memword_write(CPU_SS, sp - 2, CPU_DS);
+		i286_memword_write(CPU_SS, sp - 4, CPU_SI);
+		i286_memword_write(CPU_SS, sp - 6, CPU_DI);
+		i286_memword_write(CPU_SS, sp - 8, CPU_ES);			// +a
+		i286_memword_write(CPU_SS, sp - 10, CPU_BP);		// +8
+		i286_memword_write(CPU_SS, sp - 12, CPU_DX);		// +6
+		i286_memword_write(CPU_SS, sp - 14, CPU_CX);		// +4
+		i286_memword_write(CPU_SS, sp - 16, CPU_BX);		// +2
+		i286_memword_write(CPU_SS, sp - 18, CPU_AX);		// +0
+		TRACEOUT(("bypass to %.4x:0018", seg << 8));
+		TRACEOUT(("AX=%04x BX=%04x %02x:%02x:%02x:%02x ES=%04x BP=%04x",
+							CPU_AX, CPU_BX, CPU_CL, CPU_DH, CPU_DL, CPU_CH,
+							CPU_ES, CPU_BP));
+		sp -= 18;
+		CPU_SP = sp;
+		CPU_BP = sp;
+		CPU_DS = 0x0000;
+		CPU_BX = 0x04B0;
+		CPU_AX = seg << 8;
+		CPU_CS = seg << 8;
+		CPU_IP = 0x18;
+		return;
+	}
+#endif
+
 	switch(CPU_AL & 0xf0) {
 		case 0x90:
 			ret_ah = fdd_operate(DISKTYPE_2HD, 0, 0);